Telephone system.



PATENT ED FEB. 26, 1907.

No. 845,533. v W. w. DEAN.

TELEPHONE SYSTEM.

APPLICATION FILED FEB. 7, 1903.

UN TED sintgns PATENT OFFICE.

ILLI M w. DEAN? or CHICAGO, ILLINoIs, A SSIGNOR TO KELLOGG SWITQHBOARD AND SUPPLY COMPANY, OF CHICAGO, ILLINOIS, A GORPORATION OF- ILLINOIS.

TELEPHONE SYSTEM.

Nae rates.

' To It whom it may concern:- I

1 Be it known that 1, WILLIAM W. DEAN, a citizen of the United States of America, and

residing in Chicago, in the county of Cookand State of Illinois, have invented a new and useful Improvement in Telephone Systems, of which the-following is a specification;

In my Reissue PatentNo. 12,090, dated March'3, 1903, I have shown and described a I trolling the testing-circuit and the talkingcircuit I provide. an auxiliary relay'which is preferably initially operated by means of extra contacts provided upon the ringing-key The invention further contemplates lock ing said auxiliary relay after the operation of the ringingekey and to provide the same with 1 operating-current through the closed contacts ofa supervisory relay that is actuated over a ortion of the talking-circuit during an esta lished connection. This arrangement results in maintaining said auxiliary relay actuated during the connection and after the called subscriber ha been called. v

My invention is illustrated in the accompanying drawings, in which the same reference characters are used throughout to indicate like parts, and in which Figure 1 is a diagram of twosubscribers lines and the central-oflice apparatus by which they may be connected for conversation, and Fig. 2 is a diagram showing a modified form or arrangement ofthe actuatingcircuit of the auxiliary relay.

' Referring to Fig. 1, L and L indicate subscribers lines extending in two limbs 2 and 3Ifrom their res 'ective substations to the. centralofiice, at w 'ch latter oint they are provided with answering-j ac s J and with any suitable number of multiple jacks J normally disconnected from the external linecircuit, but. adapted to be connected therewith during conversation by means of the forward contacts of the. cut-off relays R, which are legged to ground from'the sleeve-conduc:

Specification of Letters Patent. Application filed February 7,1903. Serial 110.112.292.

Patented. Feb. 26,1907.

tors of the switchboard-sections of the lines. The line conductor2 is normally grounded or connected-with a common return at the cen- 'tral ofiice; while the conductor 3 is normally] g ined through a contact of said cut-ofi' relay ,,with the conductor 4,1eadingto the linerelay R, which controls through its normally,

o ileln contacts thecir'cuit of the line-signal S, w ch is preferably in the form of a small incandescentlamp, said relay R being thence connected-by conductor 5 with the live'pole of a grounded battery B. The line L is shown as of the polystation type and is provided at the central 'ofiicc wlth apparatus:

similar to that of the line L and is connected by means of conductor 5 to the live pole of a second battery B The substation apparatus is of the same type as is shown in my Patent No. 747,331, dated December 15, 1903, and consists, generally speaking, of abell 6, normally in circuit with a condenser 7 in the path of ringing-current, and a receiver -8, transmitter 9, and retardation-coil 10, adapted to be suitably connected in the circuit'by the switch-hook -1 1 when the receiver is taken up and the call-bell branch broken. At the two stations upon the line L?- the bells are legged to ground from the op osite sides of the line, while .at'station A t e bell is connected in the metallic line. The operator's equipment includes a cord-circuit provided with. an answering-plug P and a calling-plug P each having tipand sleeve contacts adapted to register with the'corresponding contacts of the -spring-jacks of the lines. The tip-contacts of, the plugs are joined by the strands t and t and the interposed condenser 0, while the sleeve-contacts are electrically connected by the fiexiblestrands s and s and the interposed condenser 0 The batteryB is bridged across the answering end of the cord-circuit and includes upon either side supervisory relays r and 11 which control, the former through its normally closed contacts and the latter through its normally open contacts, the local circuit of the supervisory lamp trollin the local circuit of the su ervisory lamp J, associated with the cal ing-plug.

An auxiliary relay 1*? has its winding upon one side joined by conductor 12 with the conductor 13,1eadin to one of the normally open contacts of the s eeve-relay 1", while u on its other side said relay is connected by a ranch 14 with the contacts 15 and 16 ofthe ringing key, which are adapted when actuated to ground the said branch 14. Said relay is provided with a contact 17, adapted to close alocking-circuit for said relay, and with a second contact 18, adapted normally to open the tip-strand t of the c0rdcircuit and to close the forward portion thereof upon'the conductor 19, which leads to the high-impedance and high-resistance test-relay r, the

opposite terminal ofwhich is grounded. The

operators head-telephone is adapted tobe bridged across the calling end of the cord-circuit by the springs 20 20 of the listening key while her transmitter 2 1 is preferably charged from the battery B through the retardation- ,coil 22, included in conductor 23. The primary winding of the operators inductioncoil together with a condenser arein shunt of the transmitter, and'a point upon said shunt 3 5 r call the central office closes a path for current from the'battery B, located atthe central office overthe 7' telephone-line and through. the line-relay R thus actuating the line-signal Sb Upon observing this signal the operator inserts the answering-plug P of an idle cord circuit into the answering-jack J of the calling-line and depresses her listening-key 20 to receive the order of the subscriber. The act of making the connection closes a path for current through the cut-off relay R from the battery B, which actuates said re-- lay to out ofl thev line-relay and to connect the switch-boardsection of the line with the external line-circuit. The sleeve supervisory relay 1' is also actuated at this time to close a local'ci'rcuit of the supervisory signal S but 'owing' to the fact that the 'subscribers telephone is in use the tip supervisory relay 1 receives current over the metallic line from said battery B and is actuated to open the circuit of the supervisory lam'p, which'therefore remains inert. Ascertaining that it is a subscriber located upon the line L who wanted, the condition of the line is tested in the usual manner by touching the tip of the calling plug to the test contact orring of one of the multiple. jacksof th'e said line; 'Normally these test contactsor rings are ground-' ed, and. since the tip-contact of the plug P is also normally grounded through the spring 18 of auxiliary relay r conductor 19, and the test-relay 1* no flow of current-results'and no busy click is received. When the line is connected for -conversation,,however, the testrings are connected through the sleevestrand of the connected cord-circuitwith the live pole of a battery, and when the grounded tip of the plug is brought into contact therewith a suflicient'flow of current results to ac- 7 5 tuate saidtest-relay and permit a'flow 0f'cur rent through the operators induction-coil. This causes a click in the operator s receiver and indicates to her that. the line is 1 Assuming-that the line is found idle; the call-' 25o ing-plug is inserted in one 'of'the multiple jacks and-the proper'set of ringing-key contacts operated, In case the subscriber A is wanted springs 25 and 16 of the ringingkey are depressed, which connects the generator 24 with the tip side of'the line andcallsthe wanted subscriber. Closing the spring 16 upon its groundscontact completes a path for current through the auxiliary relay r from the live pole of the battery B through the normally open contacts of'the sleeve super visory relay r whichis now actuatedover the sleeve-strand s of the cord-circuit and through the cut-0E relay ofthe line and thence over conductors 13 and:12, through said relay 1*", conductor 14, andspring 16 to ground. As soon as this relay operates-its locking-circuit is closed through contact: 17-,"

which serves to prevent demagnetizing the same as long as the sleeve-relay rismagnet- I00 ized. At the same time springlBof'saidirelay disconnects the test-relay and' completes the strand t for talking. If the subscriber-D is wanted, the ringing-s rings 26' and 15' 5f 1 the operatorsringingey aredepressed; re 5 with the result that the ringing-generator 24 is connected with the sleeve side of 'theline and calls-the wanted subscriberv It is desired to maintain the relay 1" and a cut-off relay R actuated during-ringing,- so that the no relative resistances of these parts aresuit ably proportioned topermit of this action during the period of'sending the ringing-current. The resistance of the relays 'r andof the cut-off relay R should be sufiicient to pre- I 15 vent short-circuiting the ringing-current, and

owing to the pulsating nature of 'saidcm'rent they will be maintained actuated. By means of the spring '15. the initial operation .of said auxiliary relay is securedand'which no is afterward looked, as before describedi After calling the subscriber, I but before response, the lamp S is lightedby' current fromthe batteryB but as soonas he takes up hisreceiver current over-the metallic line 5 actuates the tip-relay r torender said signal inert. At the termination ofthe converse, tion the subscribers return-their receivers-to the hooks, thus deenergizing relays r and'r, thereby closing the circuits of the super 13 other suitable manner to receive the busy visory signals, which are lighted to indicate du wn the connection, thus'restoring all parts to normal condition.

In Fig. 2 the conductor 12 leads from the relay 1'? to the normally open-spring-contact of the answering-sleeve I relay 1- whereby when said sleeve-relay is actuated current is derived from the battery B to.-'actuate said auxiliary relay. Otherwise the connections are the s'ameas Fig. 1. This arrangement permits of the use of ringing-keys that open the sleeve-strand s of the cord-circuit during ringing without afiecting the operation of said withdraw the answering-plug from the call-- ing-lirie befo'rethe second line can be tested:

auxiliary relay. 4 It is attended with the disad, vantage that when the calling subscrib er wishes a secondconnecti'on with a different partyit is necessary for the operator'to first In Fig.1 the latter objection does not-exist.-

.While I have described two forms ofthe invention and which have been worked out for commercial pi1rp'oses,fI do not intend in all respectsto thus limit the invention, since it isobviousthat the same may bevembodied' in various forms. For example, the test-relay r may obviously be replaced-by any other test-receiving device and the impedance and resistance devices may be entirely separate from the test-responsive device. The operators receiver may be connected in a common portion ofthe testing-circuit or m any test.

Iclaim w I -1.- In a telephone system, the combination. with a telephone-line having aplurality of testing-contacts, of a cord-circuit, a relay associated therewith to control the, continu,

I testing apparatus comprising a testing-terminal to cooperate with said testing-contacts, a testing-conductor connected with said testterminal a relay to control said testingapparatus, means to actuatesaid relay in calling the wanted subscriber," andiurther means 1ncluding a supervisory relay to prevent its denergization throughout the remainder oft-he connection, substantially as described.

3. In a telephone system,.the. combinationwith a telephone-line, of a 'cord circu -t to es tablish connections with the line'for 'conver sation, a busy-testingcircuit completediover aportion of the talking-circuit. said testing circuit being common to a pluralityof cord-; circuits, means for removing said testing-circuit during conversation, asupervisory relayfor controlling said means, said means being actuated oyer a circuit independent of the talking circuit, substantially as describe'df 4; In a telephone system, the combination with a telephone-line, ofa cord circuit, a testing-circuit completed over the tip-strand of "the cord-circuit, a common testing device included in said testing-circuit, a relay to sever said common portion of'the tes'ting-cip cuit from the tip-strand of the cord-circuit, said relay being actuated'o-v'er a circuit independent of the talking-circuit, the supervisory rel ay associatedwith the cord circnit and adapted to control the circuit through said first-mentioned relay, substantially as described. v

5 In a telephone system, the combination witha telephone-line, of a cord-circuit, a test ing-circu t completed over one of the strands of the cord-circuit, said testing-circuit hav- 'ing a portion common to a plurality of"cor' dcircuits, a relay for removing said common portion during conversat on, meansfor m1- tially operating said relay during ringing, a

locking-circuit for said relay to maintain the same actuated duringthe remainder of-a connection, and a supervisory relay for controlling said locking-circuit, substantially as describe Signed by mefat Chicago, county of Cook, State of-Illinois, this 29th day ofJanuary,

1903. "WILLIAM W. DEAN.

Witnesses;

ROBERT LEWIS AMES, GAzEIZ-LE BEDER. 

